Dental caries is one of the most common chronic infectious diseases in the world. The occlusal (biting surface) and interproximal (between teeth) areas are where there need for quantitative imaging of tooth decay and depth of cracks in the USA. In addition a majority of the caries load in USA is carried by different groups, such as Alaska Native people who have many times the national rate of tooth decay. Health care disparities in this population are exacerbated by rural remoteness. The average number of dental fillings per Alaskan Native person is double that of urban dwellers. To provide safe, high-quality dental care in these remote areas, an x- ray replacement is desired which provides high-resolution optical images of cracks and decay deep within teeth that does not require ionizing x-ray radiation. The current problem is that the optimal wavelengths of infrared light (1310 and 1460 nm) that can be used to see decay in teeth, do not have small high-resolution cameras for pediatric clinical use. Thus, an alternative method of forming infrared images will be developed and tested that produces the highest contrast of the lesion, which is scanning laser light either i transmission, reflection, and in a right-angle configuration (for example, scan the occlusal surface and detect above the gum line). The smallest laser-based imaging device has been developed at the University of Washington (UW), being the diameter of a round toothpick (1.2-mm) while producing high-quality video images at multiple wavelengths. The scanning fiber endoscope (SFE) technology has been tested by Dr. Joel Berg in children at The Center for Pediatric Dentistry with shared administration from UW Pediatric Dentistry and Children's Hospital, Seattle, WA. Although this device used visible light for testing the health of the enamel the change to infrared is straightforward, allowing much deeper imaging of cracks and carious lesions using optimal laser wavelengths for high-contrast transmittance and reflectance imaging. The small size of the scanner allows the two imaging modes to run concurrently if needed to find the extent of a crack, maximum depth of caries, and even total volume of caries under surveillance with non-surgical medicinal therapies. The hand piece will be smaller than any bitewing radiographic sensor used in children now, while providing new features of imaging during restorative work, possibly under tele-medicine conditions. The SFE technology is fundamentally low in cost because it uses laser and detectors that are fully developed in the telecommunications industry. The low- power scanned laser light imaging can be made portable and carries no significant risks. This project will fabricate a prototype device, determine its optimal imaging modes (wavelength &configuration), develop new 3D imaging algorithms, test with extracted teeth and verify with a pilot study with children 6 to 12 years of age.